1. Field of the Invention
The present invention relates to a structure to secure a resolver to a brushless motor.
2. Description of the Related Art
A resolver is usually used in a brushless motor in order to detect a rotational position of a rotor magnet arranged in the brushless motor. The resolver includes a resolver stator having at an inner circumference thereof a plurality of teeth, and a resolver rotor arranged radially inwardly of the resolver stator. The resolver rotor arranged in a concentric manner with the rotor magnet rotates with the rotor magnet in a uniform manner.
An excitation winding or an output winding is wound around each tooth. When the resolver rotor rotates, its radial gap formed between the resolver stator will be modified causing a voltage generated by the output winding to be changed. The resolver detects the change in the voltage so as to detect the rotary portion of the rotor magnet within the brushless motor.
The excitation winding or the output winding wound around each tooth is connected to one end of a terminal member arranged at the resolver stator. The lead wire is connected to the other end of the terminal member. The lead wire connects an external control apparatus and the resolver.
As described above, the resolver detects, based on the modification of the gap between the resolver stator and the resolver rotor, the rotational position of the rotor magnet of the brushless motor. Therefore, precise alignment between the resolver stator and the resolver rotor has a significant effect on the accuracy of detection of the resolver, and thus, a reliable and secure connection between the resolver and the brushless motor becomes crucial. Also, when a brushless motor having therein such a resolver as described above is used in an automobile or the like, an area in which the brushless motor will be arranged has a limited space therefor, and therefore, it is preferable that the resolver is as small as possible.
A method of connecting the resolver to the brushless motor by using a screw via an attachment portion arranged at an outer circumferential side of the resolver stator has been available. Such method, however, requires a space for the screw increasing the size of the resolver stator in a radial direction. Also, using the screws increases the manufacturing cost of the resolver.